TBI vs Port Injected

nacelp nacelp at bright.net
Wed Mar 22 03:11:10 GMT 2000


> So Grumpy...
> I have missed some of this thread but I'm guessing that you're talkin'
> optimized TBI vs optimized Carb...

Is there anything else?  <g>

> I would expect similar peak power and torque...

With a given manifold yes, but lots of folks mix apples and oranges at this
stage thou

> Somewhat better cold starting and warm-up driveability for the TBI
rig...but
> what about normal warm driveability...I'm assuming you're talkin' either
> Q-Jet's or AFB's with regards to the Carb's...

Warm, cold, what ever the only really difference (in N/A applications) is
not having a float bowl.  When I talk about ecms, and carbs usually I'm
talking about the CCC Q-Jet.

> Can a well optimized Carb equal the overall warm driveability and
performance
> of a well optimized TBI system?

As good, easy..  Both can be dialed in to be ideal.  Both take lots of time.
Like I said when optimized the only difference is the flaots, and the
problems with high lateral acclerations, decelerations etc.

> My well-tuned Q-Jet (71 Vette...406/375) seems to have similar warm
throttle
> response and driveability as that of my 88 Mopar OEM TBI Van (within the
> Carb's limited altitude range of course)...

Well tuned or fully optimized.  BIG difference.
Grumpy
> Thanks...
> Doug
> nacelp wrote:
> > The engine was first optimized using single, and dual plane manifolds.
I
> > doubt the is a EFI manifold that outflows a Weiand 7525 (both in stock
> > form).  The times/trap speeds were a wash, it was too close to call.
The
> > TBI had all the best manners in the world.  I know carbs really well so
when
> > I say optimized I'm including idle circuit, transistion, acclerator
pump,
> > secondary air valve, secondary needles, and hangers, air cleaners, etc.
> > They were both tweaked as far as a *normal* person would go.
> > Grumpy


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